Extension of my random on interval demo

client.js

Template.randomImg1.img = function () {
   return imgs.findOne({_id: Session.get('randomImg1') });
};

Template.randomImg2.img = function () {
   return imgs.findOne({_id: Session.get('randomImg2') });
};

Template.randomImg3.img = function () {
   return imgs.findOne({_id: Session.get('randomImg4') });
};

Template.randomImg4.img = function () {
   return imgs.findOne({_id: Session.get('randomImg4') });
};


SetInterval(function () {
   Meteor.methods('getRandomImg', function (err, _id) {
       Meteor.subscribe('imgById', _id);
       Session.set('randomImg2', _id);
   });
}, 5 * 1000);

SetInterval(function () {
   Meteor.methods('getRandomImg', function (err, _id) {
       Meteor.subscribe('imgById', _id);
       Session.set('randomImg3', _id);
   });
}, 30 * 1000);

SetInterval(function () {
   Meteor.methods('getRandomImg', function (err, _id) {
       Meteor.subscribe('imgById', _id);
       Session.set('randomImg4', _id);
   });
}, 10 * 1000);

SetInterval(function () {
   Meteor.methods('getRandomImg', function (err, _id) {
       Meteor.subscribe('imgById', _id);
       Session.set('randomImg1', _id);
   });
}, 15 * 1000);

server.js

var randomWithinRange = function randomWithinRange (min, max) {
  return Math.floor(Math.random() * (max - min + 1)) + min;
};

Meteor.methods({
   'getRandomImg': function () {  
       var numToSkip = randomWithinRange(0, imgs.find().count());
       return imgs.findOne({}, {limit: 1, skip: numToSkip})._id;
   }
});

Meteor.publish('imgById', function (_id) {
    check(_id, Number);
    return imgs.find({_id: _id});
});